Synthesis, Crystal Structure and NLO Properties of a Novel Ruthenium(II) Complex with Unusual Coordination Mode

Abstract

A new Schiff base 4- [N-hydroxyethyl-N-(methyl)amino]benzaldehyde S-methyl dithiocarbazate (HL, where H is a dissociable proton) and the ruthenium complex [Ru(bpy) 2 L]PF 6 (bpy = 2,2¢-bipyridine) have been synthesized. The structural determinations of the ligand and its ruthenium complex, by X-ray crystallography, show that the ligand is coordinated as a monoanionic bidentate N, S-donor, forming a four-member chelate ring with a bite angle of 65.91°. The complex shows intense MLCT transitions in the visible region. Fluorescent and electrochemical properties have been also studied. The complex in DMF solution exhibited a strong twophoton absorption (t.p.a.) at 532 nm nanosecond laser pulses. The t.p.a. coefficient b, t.p.a. cross-section r and the third-order optical nonlinearity v (3) of the complex and the ligand have been determined by the Z-scan technique.

Excited-State Dynamics and Two-Photon Absorption Cross Sections of Fluorescent Diphenyl-TinIV Derivatives with Schiff Bases: A Comparative Study of the Effect of Chelation from the Ultrafast to the Steady-State Time Scale

“…Mainly, the remarkable increment in the fluorescent state lifetime of more than 50 times when the Schiff bases 1 and 2 are coordinated to a diphenyl-tin IV moiety indicates that the effect of chelation with a tin IV center reduces the rate of the nonradiative channels and avoids possible E − Z isomerization processes, dramatically enhancing the lifetime of the first electronically excited state. It is worth noticing that this effect is not exclusive of tin, because there are some other combinations of Schiff bases with metals that are also highly fluorescent or phosphorescent. ,– ,,,, In this respect, the chelating center can be seen as the molecular feature that stands for the stabilization of the S 1 state by “holding” or restricting the organic Schiff base skeleton and avoiding the loss of excitation energy through internal conversion to the ground state, or isomerization. , The variations of the decay times and quantum yields within the complexes can be rationalized by considering recent calculations of the potential energy surfaces of Schiff bases . Such studies indicate that the fluorescence quantum yield of the ligands involved in series 3 and 4 is determined at least in part, by competition between radiative decay, E − Z isomerization, and direct internal conversion to the ground state.…”

Ruthenium(II)/(III) complexes of 4-hydroxy-pyridine-2,6-dicarboxylic acid with PPh3/AsPh3 as co-ligand: Impact of oxidation state and co-ligands on anticancer activity in vitro

“…The electrochemical data are given in Table values are concurrent with the literature reports. 17, 18 In addition, a quasi-reversible cathodic process occurring at -0.58 V versus Ag/Ag + with peak-to-peak separation of 225 mV can be safely assigned to a ligand based redox response on comparing with the electrochemical data of H 2 hpa and it is attributed to the formation of the hpa radical anion. An oxidation couple observed with formal potential 1.45 V is quasi-reversible (DE p = 161 mV) and it is assigned to the Ru III /Ru II redox process.…”

Synthesis, luminescence and cyclic voltammetric studies of several novel carboxylato diruthenium complexes

“…The single-photon fluorescent (SPF) data and absorption spectra in six different solvents were collected (as shown in Table 4) and the solvent influence on fluorescence was discussed with the Lippert-equation [30]. The single-photon fluorescence spectra of the complexes Ru 2 (L 0 ) 4 Cl, Ru 2 (L 1 ) 4 Cl and Ru 2 (L 2 ) 4 Cl resemble those of the free ligands L 0 , L 1 and L 2 , respectively.…”

“…The Stokes' shift is defined as the loss of energy between absorption and reemission of light, which is a result of several dynamic processes. The Lippert equation is the most widely used equation to describe the effects of the physical properties of the solvent on the emission spectra of fluorophore [30].…”